Portable electronic device



FIG. 1 is an elevational view of a casing for tablet electronic device showing our new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a left side elevational view thereof;

FIG. 4 is a right side elevational view thereof;

FIG. 5 is a top plan view thereof;

FIG. 6 is a cross-sectional view thereof taken along line 6-6 of FIG. 1; and,

FIG. 7 is a cross-sectional view thereof taken along line 7-7 of FIG. 1.

The broken lines shown in figures illustrate environmental structures and form no part of the claimed design. 

CLAIM The ornamental design for a casing for tablet electronic device, as shown and described. 